Vagus nerve stimulation (VNS) may be a novel therapeutic treatment for post traumatic disorder, PTSD, a team of University of Texas scientists reported.

The scientists presented their findings at the Neuroscience Conference 2016 in November.

VNS therapy is used to prevent seizures by sending regular, precisely timed, mild pulses of electrical stimulations from an implant device, which works like a pace maker, to the brain via the vagus nerve.

The vagus nerve is part of the autonomic nervous system, which controls functions of the body that are not under voluntary control, such as the heart rate. It passes through the neck as it travels between the chest and abdomen and the lower part of the brain.

To facilitate VNS, minimally invasive surgery is required to place the nerve-stimulating electrode in the neck under the skin. VNS is safe for human use, and since US FDA approval in 1997, over 80,000 patients have been implanted for prevention of seizures and treatment of depression.

In their research, the scientists induced single prolonged stress, an animal model of PTSD, in rats. The PTSD rats and another group of normal control rats were both fear-conditioned for two days.

The rats were then given daily exposure therapy, a reconditioning-training for the elimination of the conditioned fear, either with VNS or with sham stimulation.

Note: Currently, exposure therapy is the most widely used treatment for the 22.4 million people living with PTSD in the US. It is a form of cognitive behavioural therapy. Patients are repeatedly exposed to cues that remind them of the trauma until they learn that cues once associated with danger are no longer threatening.

Unfortunately, failure to learn or incomplete learning often results in drop out or nonresponse. Also, some patients found the therapy intolerable. As many as 50% of PTSD patients are resistant to exposure therapy.

In this study, the rats were then tested one week and six weeks later for the typical symptoms of PTSD including hypervigilance (easily startled), avoidance (avoid reminders of conditioned fear), and general anxiety.

Researchers found that exposure therapy paired with VNS brought the fear expression of the PTSD-model rats to the levels of the control rats. Also, typical symptoms of the PTSD-model rats had all improved even after just one week.